you need his identity documents to make a family tree . you can rely upon court order to prove that he has no share in property . you can use ration card if he is not willing to give aadhar card 

ask your siblings to intervene in the matter 

The tahsildar has powers to give notice to the said relatives to provide necessary information. If not given he will pass exparte orders 

 It's not clear in question regarding the location of the property in India. If it were to be in Karnataka State, you can obtain the Khatha in your father's name by producing the Court order in respect of your uncle and in respect of other legal heirs registered Release/Relinquishment Deed.

Father can apply for khata in his name 

enclose death certificate of grand father 

release deed signed by his siblings 

latest receipt of payment of property taxes 

affidavit for mutation of property in his name 

This property belonged to your grandfather which devolved on all his legal heirs.

It is reported that your father's elder brother had filed a suit for partition.

your father was a party to the suit.

The partition suit would contain the names of all the legal heirs because all are necessary parties to suit.

Therefore the copy of the plaint itself is a documentary evidence to prove the legal heirs/family tree members of the family of your grandfather. 

Even otherwise, you can prepare an affidavit mentioning the names of all the legal heirs of your grandfather and get this affidavit notarised under the affidavit for family tree certificate, that will solve the purpose. 

It is not essential to mention their aadhar card number or any other identity proof of all the members accommodated in the family tree certificate. 

You do not have to beg him to produce the documents to you for this purpose.

You can use the court order containing the name of the parties who are all the legal heirs of your grandfather to proved the relationship in the family tree affidavit.

On the basis of the said documents in your possession you can prepare an affidavit duly notarised giving the details of the members of the family of your deceased grandfather and can apply for khata accordinlgy. 

Since you have the requisite documents, go to Bangalore One and submit all the original documents for scanning and for onward submission to BBMP to obtain Katha. The original documents will be immediately returned to you after scanning in Bangalore One office. If in case family tree is essential, get a notarised family tree, without having to contact your uncle.

Yes they are enough 

1. You shall have to avail the legal heir certificate from the Tehshilder or Ward Councilor of your area.

2. While issuing the legal heir certificate, the Tehshilder or the Ward Councilor will ask for an affidavit from your side showing the family tree.

3. If the eldest son is not providing his Aadhar Card etc, you can attach the Court order wherein his share has been settled by your father by paying him the cost to get the said certificate of legal heirs.

Attach the Court order wherein he has been shown as one of the legal heirs to solve the problem.

1. Your father already possesses the Court orders which shows the names of all the legal heirs.

2. Based on the said Court orders, the identity of all the legal heirs can be easily established for which a family tree or legal heir certificate from the Tehshilder or Ward Councilor will not be required.